Semiconductor modules have electrical connections for the purpose of their external electrical connection. Since semiconductor modules often switch very heavy currents, at least the load electrical connections must have a high current-carrying capacity. In previous solutions, the electrical connections are formed by connection ends of metal plates.
According to one variant, the metal plates are fed through the module housing so that the connection ends lie on the outer side of the housing. Subsequently, each connection end is bent in such a way that it covers a screw nut which is placed in a recess of the housing. By it being possible to pass a screw through the connection end and through a connection conductor external to the module and twist it into the screw nut, the connection conductor external to the module can be electrically conductively connected to the connection end. Since thick metal plates are used in order to produce the electrical connections, because of the required high current-carrying capacity, the bending requires strong forces which are transmitted via the metal plate into the interior of the module, so that damage can occur inside the module. Furthermore the bending cannot be carried out with the desired precision, the effect of which is that the height of the semiconductor module cannot be adjusted precisely. If a connection conductor external to the module is intended to be screwed together with a plurality of connection ends thereof or a plurality of neighboring semiconductor modules, this can lead to mechanical stresses and therefore damage of a semiconductor module and/or of the connection conductor external to the module.
According to another variant, during production of the module housing, pre-bent metal plates are injection-molded into the latter so that the connection ends protrude out of the module housing. Since the metal plates and the housing plastic have very different thermal expansion coefficients, because of cyclic thermal loads mechanical stresses can likewise occur, and therefore damage to the semiconductor module.
Another problem which frequently arises with semiconductor modules consists in high stray inductances of the electrical lines built into the module, since in this way undesired high induction voltages can occur in the event of rapid current variations. In order for two lines carrying high voltage to have a low inductance, it is advantageous for these to be configured as flat strips which extend parallel to one another with a small spacing, while being electrically insulated from one another. Such lines, however, can only be produced in a semiconductor module with great outlay. One possibility consists in installing two metal conductors one after the other with a small spacing and electrically insulating them from one another with an encapsulation compound, with which the module housing is subsequently filled and which flows between the two conductors. So that short circuits do not inadvertently occur in this case between the conductors, a sufficient safety distance between them must be set. Because of manufacturing tolerances, however, this needs to be kept relatively large. Another problem may be air inclusions in the encapsulation compound. If such air inclusions occur between the two conductors, for example, the insulation strength is locally reduced there and partial discharges may occur. Another possibility of electrically insulating two conductors from one another is to place prefabricated insulation layers between them. This, however, entails great outlay in terms of manufacturing technology. Furthermore, air inclusions may be formed at the insulation layers during subsequent filling with an optional encapsulation compound, again with the effect that the insulation strength is locally reduced there and partial discharges may occur.